Even if you have the best valvetrain components in your race engine, improper installation and alignment can leave it huffing and wheezing like a back-of-the-pack hunk of junk. Worse, poor valvetrain alignment will lead to accelerated wear which can cause parts to wear out and break before you even make it to rebuild time.
1 Most cylinder heads for Chevrolet small-blocks have bolt holes for the rocker studs tha
There are also plenty of times you may need to work on your race engine's valvetrain for general maintenance. Inexpensive stock valvesprings in crate engines help manage costs, but they are also prone to losing pressure and must be replaced regularly. Engines running flat tappet lifters must also have the lash on all the valves regularly checked. Finally, you may attempt to repair or rebuild your own race engine and must make sure that the valvetrain is assembled as well as possible.
While reassembling Circle Track's Dyno Mule Chevy 350 for an upcoming story, we also had the opportunity to try out Lunati's new Voodoo aluminum rocker arms. These new Lunati rockers are full roller to minimize friction and feature oiling galleries to lubricate and cool the valvesprings as well as the trunion and roller tip. They are also machined to provide plenty of clearance for high-lift aggressive cam profiles--which fits the need for the solid roller Comp camshaft we're using that produces 0.610 lift at the valve.
We'll fire up the dyno mule in a future issue for some interesting tests. But in the meantime, we thought we'd pass along a few tips for making sure your valvetrain is working as efficiently as possible. So without further ado, here they are.
-
2 The rocker studs don't require Loctite but should all be torqued to 50 ft-lb using thre
-
3 We were lucky to get our hands on Lunati's new aluminum Voodoo rocker arms. These are 1
-
4 The rockers have oiling galleries to feed oil to both the roller tip and the valvesprin
-
5 After submerging the Comp Cams solid roller lifters in motor oil, they were installed i
-
6 Since this is the first time we've run this engine combo with the new Lunati rockers, w
-
7 If this is a new build or you don't have a variety of different pushrod lengths on hand
-
8 The length of the pushrod determines where the tip of the rocker arm contacts the top o
-
9 Next, install the rocker arm and install the lock nut so that you have zero lash.
-
10 Bump the engine over several revolutions so that the valve you are checking opens and
-
11 Here, you can see the difference in two different pushrod lengths. We started with the
-
12 Here's a shot of the two Comp pushrods we used. As you can see, there isn't much diffe
-
13 Once you have your correct pushrods, take a moment to clean them thoroughly. Even if t
-
14 Before installing your rocker arms for the final time, check to make sure the trunion
-
15 Check with your camshaft manufacturer for the suggested valve lash if you're running a
-
16 Once you have the proper lash, tighten the locking screw inside the nut to lock it dow
-
17 Lash should only be checked when the lifter for the valve you are checking is on the c
-
18 Here's the rocker fully lashed and ready to go. Notice that the roller tip contacts th
-
19 As the valve opens, the tip of the rocker rolls across the center of the valve stem ti